The 3D structure of the catalyst layer (CL) in the polymer electrolyte fuel cell (PEFC) is modeled with a Pt/carbon (Pt/C) ratio of 0.4–2.3 and ionomer/carbon (i/C) ratio of 0.5–1.5, and the ...structural properties are evaluated by numerical simulation. The models are constructed by mimicking the actual shapes of Pt particles and carbon aggregates, as well as the ionomer adhesion in real CLs. CLs with different compositions are characterized by structural properties such as Pt inter-particle distance, ionomer coating thickness, pore size distribution, tortuosity, and ionomer coverage on Pt. The results for Pt/C = 1.0, i/C = 1.0 with Pt loading of 0.3 mg cm−2 and 50% porosity are validated against measured data for CLs with the same composition. With increasing i/C ratio, the smaller pores disappear and the number of isolated pores increases; while the ionomer connection and its coverage on Pt are significantly enhanced at i/C ∼1.0. With increasing Pt/C ratio, the Pt inter-particle distance decreases as the particles connect with each other. The tortuosity of the pores and the ionomer exhibits a trade-off relation depending on the ionomer volume. Further CL design concepts to optimize both O2 diffusion and H+ conduction are discussed.
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•3D catalyst layer (CL) structure in polymer electrolyte fuel cells is modeled.•Calculated pore, Pt particle, and ionomer configurations validated with experiments.•Effects of Pt/C and ionomer/C ratios on CL structure and performance are estimated.•New design concepts based on balancing several trade-offs are proposed.
We reviewed epidemiologic studies of cigarette smoking and the risk of cervical cancer among Japanese women, and we conclude that cigarette smoking convincingly increases the risk of cervical cancer.
...Abstract
Background
There is a body of evidence to suggest that cigarette smoking increases the risk of cervical cancer in women, but no study has examined the magnitude of the association in Japanese women. Here, we evaluated the association between cigarette smoking and the risk of cervical cancer in Japanese women based on a systematic review of epidemiological evidence.
Methods
Original data were obtained from a MEDLINE search using PubMed or from a search of the ‘Ichushi’ database, as well as by a manual search. Evaluation of associations was based on the strength of evidence and the magnitude of association, together with biological plausibility as evaluated previously by the International Agency for Research on Cancer. Meta-analysis of associations was also conducted to obtain a summarized overview of the data.
Results
We identified two cohort studies and three case-control studies. All five studies had indicated strong positive associations between cigarette smoking and the risk of cervical cancer. Our summary estimate indicated that the relative risk (RR) for individuals who had ever-smoked relative to never-smokers was 2.03 (95% confidence interval: 1.49–2.57). Four studies had also demonstrated dose–response relationships between cigarette smoking and the risk of cervical cancer.
Conclusion
We conclude that there is convincing evidence that cigarette smoking increases the risk of cervical cancer among Japanese women.
Background
High morbidity and mortality rates after pancreaticoduodenectomy (PD) have led to concentration of this surgery in high‐volume centres, with improved outcomes. The extent to which better ...outcomes might be apparent in a healthcare system where the mortality rate is already low is unclear.
Methods
The Japanese Diagnosis Procedure Combination database was used to identify patients undergoing PD between 2007 and 2010. Patient data included age, sex, co‐morbidities at admission, type of hospital, type of PD, and the year in which the patient was treated. Hospital volume was defined as the number of PDs performed annually at each hospital, and categorized into quintiles: very low‐, low‐, medium‐, high‐ and very high‐volume groups. The Charlson co‐morbidity index was calculated using the International Classification of Diseases, tenth revision, codes of co‐morbidities.
Results
A total of 10 652 patients who underwent PD in 848 hospitals were identified. The overall in‐hospital mortality rate after PD was 3·3 per cent (350 of 10 652), and for the groups ranged from 5·0 per cent for the very low‐volume group to 1·4 per cent for the very high‐volume group (P < 0·001). Multivariable analysis revealed a significant linear relationship between higher hospital volume and shorter postoperative length of stay compared with the very low‐volume group, and between increasing hospital volume and lower total costs.
Conclusion
A significant relationship exists between increasing hospital volume, lower in‐hospital mortality, shorter length of stay and lower costs for patients undergoing PD in Japan. Centralization of PD in this healthcare system is therefore justified.
The volume effect is important even when mortality is low
Synchrotron monochromatic-beam x-ray topography observation has been performed on high-quality ammonothermal gallium nitride single crystal to evaluate threading dislocations (TD) in a nondestructive ...manner. Asymmetric diffractions with six equivalent
g
-vectors of 11–26, in addition to a symmetric diffraction with
g
= 0008, were applied to determine the Burgers vectors (
b
) of dislocations. It was found that pure edge-type TDs with
b
=
11
-
20
/
3
did not exist in the sample. A dominant proportion of TDs were of mixed type with
b
=
11
-
20
/
3
+
0001
, i.e., so-called
c
+
a
dislocations. Pure 1
c
screw dislocations with
b
=
0001
and TDs with
c
-component larger than 1
c
were also observed.
The sagittal split ramus osteotomy (SSRO) has been performed mainly on an inpatient basis because of the duration of anaesthesia and the potential risk of postoperative complications, such as ...bleeding, pain, nausea, and vomiting. However, advances in both surgical and anaesthetic management have enabled the reduction of these risks and shortened the length of hospital stay. Thus, the SSRO may be feasible even in the ambulatory setting in elective cases. The clinical records of all patients who underwent an outpatient SSRO between August 2011 and September 2020 at Lilla Craniofacial Clinic were reviewed retrospectively. Data on age, sex, duration of surgery, operative procedures, intraoperative bleeding, and admission status were investigated. In total, 143 patients underwent a bilateral SSRO. The SSRO was performed as an isolated procedure in 73 patients and concomitantly with other surgical procedures in the remaining 70 patients. Overall, 142 of the 143 patients were discharged on the day of surgery (99.3%); only one (0.7%) required an overnight stay because of a submental haemorrhage after genioplasty. No emergency hospitalizations or readmissions occurred after discharge. Multimodal perioperative management, both surgical and anaesthetic, facilitated enhanced patient recovery after surgery, and SSRO was performed successfully and safely as an ambulatory procedure.
Oral epithelium might be the first barrier against oral bacteria in periodontal tissue. We hypothesized that oral epithelium is endowed with innate immune receptors for bacterial components, which ...play roles in host defense against bacterial infection without being accompanied by excessive inflammatory responses. We found clear expression of Toll-like receptor (TLR)4 as well as TLR2, and strong expression of NOD1 and NOD2 in normal oral epithelial tissues by immunohistochemical analysis. We also showed that primary oral epithelial cells in culture expressed these molecules using PCR, flow cytometry, and immunostaining. In inflamed oral epithelium, cell-surface localizations of TLR2 and TLR4 were more clearly observed than in healthy tissue. Upon stimulation with synthetic ligands for these receptors, the expression of β-defensin 2 was markedly up-regulated. These findings indicate that these molecules in oral epithelial cells are functional receptors that induce antibacterial responses.
Light absorbers available at present provide far from optimal black-body performance. The need for more efficient absorbers is particularly acute on the microscale, where they can play a significant ...role in preventing crosstalk between optical interconnects, and also as thermal light-emitting sources. Several efforts have been made in this context to achieve near-total but directionally dependent absorption using periodic grating structures. However, the ability to absorb light completely for any incident direction of light remains a challenge. Here we show that total omnidirectional absorption of light can be achieved in nanostructured metal surfaces that sustain localized optical excitations. The effect is realized over a full range of incident angles and can be tuned throughout the visible and near-infrared regimes by scaling the nanostructure dimensions. We suggest that surfaces displaying omnidirectional absorption will play a key role in devising efficient photovoltaic cells in which the absorbed light leads to electron-hole pair production.
Hybrid emitting exciton-plasmonic composites are constructed by coating arrays of spherical nanovoids embedded in a gold film with organic semiconducting molecular J-aggregate films. In such ...plasmonic crystals, localized plasmons confined inside the voids can be excited. We report the first observation of polaritonic spectral narrowing and strong coupling between localized plasmons and J-aggregate excitons with Rabi splittings of 230 meV at room temperature.
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